Flashcards About Chapter 21

•  1st line of defense against pathogens
• Enter through skin breaks
• Skin mostly inhospitable for microbes
• Salt inhibits microbes
• Lysozyme breaks apart peptidoglycan
• Perspiration and sebum contain nutrients
• Moisture of armpits, etc have higher population
• Contribute to body odor

•  Line body cavities
• The epithelial cells are attached to an extracellular matrix
• Cells secrete mucus
• Often acidic
• Some cells have cilia
• In eyes, washed by tears with lysozyme

• Gram-positive, salt-tolerant bacteria
• Staphylococci
• Micrococci
• Diphtheroids

• Vesicle: fluid-filled superficial lesion
• Bulla: similar to vesicle, larger than 1 cm
• Macule: slightly raised reddish rash or lesion (Measles)
• Pustule (papule): contains pus well beneath cutaneous layer

• Gram-positive cocci, coagulase-negative (enzyme clots blood)
• 90% normal mibrobiota
• Less pathogenic
• Staphylococcal skin infection

•  Gram-positive cocci, coagulase-positive
• 20% population have in nasal passages; another 60% carry it
• More pathogenic
• Staphylococcal skin infection
• Numerous virulence factors
• Some strains produce enterotoxins
• Associated with resistance
• MRSA (methicillin resistant S. aureus)

• Infection of the hair follicles
• Pus is formed

• Folliculitis of an eyelash

• Abscess; pus surrounded by inflammed tissue
• 1-2 cm EX: boil

• Inflammation of tissue under the skin

• Crusting (nonbullous) sores, spread by autoinoculation

• Toxic shock syndrome toxin 1
• Associated with high-absorbency tampons and absorbent packing following nasal surgery

• Bullous impetigo
• Impetigo of the newborn

• Gram-positive; grow in chains
• Group A
• beta-hemolytic streptococci (lyse RBCs)
• “strep throat”
• can lead to scarlet fever

• dermal layer of skin affected; red patches
• Can cause sepsis
• Can occur in untreated strep throat cases

• Necrotizing fasciitis
• Exotoxin A
• Superantigen- antigen that activates serious immune reaction
• Mortality- 40%

• Gram-negative, aerobic rod
• produces a blue-green pus
• Otitis externa, or “swimmer’s ear”
• Post-burn infections
• Opportunistic

• Mild
• Sebum channels blocked with shed cells
• Treatment
• Topical agents
• Salicylic acid preparations
• Retinoids- vitamin A derivatives (Retin-A)

• Propionibacterium acnes
• Gram-positive, anaerobic rod
• Form fatty acids after metabolizing sebum as a nutrient; causes inflammatory response
• Treatment
• Preventing sebum formation (isotretinoin-Accutaine); causes severe birth defects
• Antibiotics
• Benzoyl peroxide to loosen clogged follicles
• Visible (blue) light (kills P. acnes)

• Severe
• Treatment
• Isotretinoin

• Warts
• Very contagious
• Treatment
• Removal
• Cryotherapy
• Electrodesiccation
• Salicylic acid

• associated with cervical cancer

• Smallpox virus (orthopox virus)
• Variola major has 20% mortality
• Variola minor has <1% mortality
• Eradicated by vaccination
• Only 2 stocks of the virus in world: CDC and Russia
• Bioterrorism concern
• Vaccination of military

• Prevention by smallpox vaccination
• 2003- US outbreak in prairie dog owners

•  Varicella-zoster virus (human herpesvirus 3)
• Mild childhood disease
• Transmitted by the respiratory route
• Causes pus-filled vesicles
• Virus may remain latent in nerves
• Prevention: Live attenuated vaccine
• Breakthrough varicella in vaccinated people
• Booster needed

• Herpes zoster
• Reactivation of latent HHV-3 releases viruses that move along peripheral nerves to skin
• Trigger- stress; lower immunity ass. With aging
• Rash unilateral
• Postherpetic neuralgia: severe burning/pain lasting years
• Prevention: Live attenuated vaccine
• Acyclovir may lessen symptoms

• 90% population infected; most subclinical
• Many cases: cold sores or fever blisters (vesicles on lips)
• Not same canker sores (different location)
• Latent in nerves- trigger sun, stress, hormones
• Herpes gladiatorum (vesicles on skin)
• Herpetic whitlow (vesicles on fingers)

•  can remain latent in nerves
• Sexually transmitted disease
• HSV-2 encephalitis: 70% fatality
• Can occur in infants born to HSV-2 positive mothers
• Treatment: Acyclovir

• Transmitted by respiratory route
• Macular rash (starting on face) and Koplik's spots
• Prevented by vaccination

;

• Macular rash and fever
• Congenital rubella syndrome causes severe fetal damage
• Prevented by vaccination

• ;Erythema infectiosum
• Name derived from a 1905 list of skin rashes, which included
• Human parvovirus B19 produces mild flu-like symptoms and facial rash
• ;slapped cheek; facial rash

;

• Caused by human herpesvirus 6 (HHV-6) and 7 (HHV-7)
• Mild childhood illness
• High fever and rash lasting for 1;2 days

• Fungal infections of the hair, nails and outer layer of skin
• Also known as tineas or ringworm
• Metabolize keratin
• Tinea capitis (scalp), tinea cruris (groin), tinea pedis (foot), tinea unguium (nails)
• Treatment- topical miconazole
• Cutaneous Mycoses

• ;may result from suppression of competing bacteria by antibiotics
• Occurs in skin and mucous membranes of genitourinary tract and mouth
• Topical treatment with miconazole or nystatin
• Fulminating disease can result in immunosuppressed individuals (HIV)
• Treatment: Fluconazole

• ;Sarcoptes scabiei: mite that burrows in the skin to lay eggs
• Inflammatory skin lesions
• Transmitted sexually; intimate contact
• Treatment with topical insecticides

• Pediculus humanus capitis (head louse)
• P. h. corporis (body louse)
• Head to head contact
• Feed on blood
• Lay eggs (nits) on hair
• Treatment with topical insecticides

• ;An inflammation of the conjunctiva
• Also called pinkeye or red eye
• Commonly caused by Haemophilus influenzae
• Various other microbes can also be the cause
• adenovirus
• Associated with unsanitary contact lenses

• ;Caused by Neisseria gonorrhoeae
• Transmitted to a newborn's eyes during passage through the birth canal
• Prevented by treating a newborn's eyes with antibiotics

• ;Causes inclusion conjunctivitis, or chlamydial conjunctivitis
• Transmitted to a newborn's eyes during passage through the birth canal
• Spread through swimming pool water
• Treated with tetracycline
• Causes trachoma
• Leading cause of blindness worldwide
• Infection causes permanent scarring; scars abrade the cornea leading to blindness